Linnaeus presents a work by Giuseppe Vianelli, in which the author reveals the true nature and cause of the phosphorescence of the sea: Nuove scoperto intorno le luci notturne.
Linnaeus has received this book from a Venetian gentleman and finds the results so interesting that he feels obliged to inform his countrymen.
Vianelli noticed that the phosphorescence appears only from early summer to late autumn, especially where there is seaweed, and the water is put in motion by waves, ships or oars.
In 1746, the author analysed such water in his home. It gleamed when he splashed it, but when he inspected the water in daylight, he could not find anything that could produce such a light. When he strained the water through a cloth, he discovered innumerable tiny glittering particles. When he analysed these particles in a microscope, he saw that they were minute worms, with eleven rings, brushes instead of feet, antennae or tentacles in both ends.
The whole bodies of these worms glitter, not just part like the glow-worms. In spring these worms keep to the seaweed, but in summer they spread in the sea, mostly in the surface. When the phosphorescence is strong at night, the fishermen take this as a sign of bad weather.
Vianell’s results prove that these worms are the cause of all phosphorescent phenomena in the sea, observations made by fishermen in Algier also described by Thomas Shaw.
Linnaeus would have wished for a more detailed description of these worms, but he believes that they must belong to genus Aphrodita.